The present invention relates to a transformer module, and more particularly, to a transformer module that is configurable to provide one or more transformer turns ratios.
A transformer is an electrical device that transfers energy by inductive coupling between two or more of its windings. A varying current in the primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic flux through the secondary winding. This varying magnetic flux induces a varying voltage in the secondary winding.
In an ideal transformer, the induced voltage in the secondary winding (Vs) is in proportion to the primary voltage (Vp) and is given by the ratio of the number of turns in the secondary (Ns) to the number of turns in the primary (Np) as follows: Vs/Vp=Ns/Np. By appropriate selection of the ratio of turns, a transformer thus enables an alternating current (AC) voltage to be “stepped up” by making Ns greater than Np, or “stepped down” by making Ns less than Np. Typically, the windings are coils wound around a ferromagnetic core.
Transformers are used in many electrical circuits to realize power transfer while providing isolation. In one application, an isolation transformer is used in a resonant converter to generate an output DC voltage from an input DC voltage while providing isolation. Resonant converters are used in high voltage applications where high frequency operation and low switching losses are desired. Common resonant converter topologies include the LC series resonant converter and the LLC resonant converter which is a modified LC series resonant converter including a shunt inductor across the transformer primary winding. The LLC resonant converter has many advantages over the LC series resonant converter. For instance, the LLC resonant converter can regulate the output voltage over wide line and load variations which a relatively small variation of switching frequency. The LLC resonant converter can also achieve zero voltage switching over the entire operating range which improves efficiency.